Formation of artificial, structured microbial consortia (ASMC) by dielectrophoresis

Artificial microbial consortia with defined internal microstructure (ASMC) were constructed by attracting cells of different microbial species to planar micro-electrodes by dielectrophoresis. Cells of Saccharomyces cerevisiae, Escherichia coli and Micrococcus luteus were deposited between the micro-electrodes sequentially to form layered cell aggregates with defined internal structures. The position of the different micro-organisms on the surface and within the cell layers was controlled by varying the electrode geometry, by introducing the different micro-organisms at different times, and by energising different parts of the electrode structure at different times. The cell arrays were stabilised using UV photopolymerised acrylamide-based hydrogels containing acrylamide and N,N′-methylene-bis acrylamide in the ratio of 15/2.2 (w/w), at a concentration of 5%. Although the viability of S. cerevisiae was only slightly affected after incubation in the monomer solution for 30 min, cells immobilised in the polymerised hydrogel exhibited reduced rates of glucose consumption and ethanol production compared with freely suspended cells, possibly due to diffusional limitation in the relatively thick hydrogels used. The gel-stabilised, structured consortia can either remain on the micro-electrode arrays as a structured biofilm, or they can be removed from the electrodes and used in a suspended form. The artificial, structured microbial consortia could be used to study microbial interactions and to create novel metabolic interactions between micro-organisms.